On some flight usually at cruising altitude the aircraft begins to put itself in high bank angles and keeps making left and right turns while LNAV.

Can anybody give some light on this issue?

Ive seen this behavior too.

Isn't this the infamous S-turn issue? I believe the solution is (1) disabling FSX turbulence effects, (2) running the Flight1 Registry Repair Tool, and/or (3) using FSUIPC wind smoothing. 

I Disabled Turbulence, I hope i can see the difference next flight.